1. Field of the Invention
This invention relates in general to an apparatus which records images by jetting a liquid imaging material in a controlled manner. More particularly, this invention relates to an apparatus for depositing ink on a receiving surface by electrostatic generation of intermittent jetting of the ink in response to a video signal.
2. Description of the Prior Art
In the past, there have been numerous attempts to effect non-impact printing by positioning a conductive platen behind a sheet of recording medium such as paper, and then attracting the ink to the platen by an electrostatic field, thereby attracting the ink to the paper. Examples of such prior art techniques may be found in U.S. Pat. Nos. 3,060,429 and 3,341,859, and in pending U.S. patent application Ser. No. 487,268, filed Apr. 21, 1983 by Ray H. Kocot for an Electrostatic Ink Jet System With Potential Barrier Aperture. The later mentioned patent application is incorporated by reference in the present application.
These prior art systems use various techniques to apply a high voltage potential to an ink jet nozzle which is supplied with ink. The applied voltage potential creates an electric field at the tip of the nozzle. The electric field exerts a force on the ink at the tip of the nozzle creating a mass flow of the ink. In all of the prior art techniques, the frequency response of the mass flow does not follow that of the electric field. As a result, the image produced by the mass flow of ink being deposited on the recording medium is not sharp.
It is the general object of the present invention to overcome these and other drawbacks of the prior art by providing an electrostatic ink jet printing system which delivers a jet of ink from an ink jet nozzle to a printing surface in a controlled manner.
It is another object of the present invention to provide an electrostatic ink jet printer which produces sharper images than produced by prior art systems.
It is still another object of the present invention to provide an electrostatic ink jet printer which includes a potential barrier which blocks the effect of stray or unwanted electrostatic charges which build up on the printing medium.
It is a further object of the present invention to provide an electrostatic ink jet printing system providing a flow of ink having improved frequency response.
These and other objects and advantages of the present invention will become more apparent from reading the following detailed description of the invention in conjunction with the drawings.